785 MPa LEVEL EXTRA-THICK QUENCHED AND TEMPERED RACK STEEL PLATE FOR OFFSHORE PLATFORMS AND PREPARATION METHOD THEREFOR

Abstract

The present invention discloses a 785 MPa level extra-thick quenched and tempered rack steel plate for offshore platforms and a preparation method therefor, wherein chemical components of the steel plate by weight percentage are: 0.08%-0.15% of C, 0.60%-1.5% of Mn, 0.10%-0.50% of Si, 0.002%-0.005% of S, 0.005%-0.015% of P, 2.7%-4.0% of Ni, 0.40%-1.00% of Cr, 0.30%-0.70% of Mo, 0.10%-0.40% of Cu, 0%-0.080% of Nb, 0%-0.10% of V, 0%-0.08% of Ti, 0.02%-0.08% of Al, 0.0008%-0.0015% of B, and the balance of Fe and other unavoidable impurities. The present invention adopts a low C, high Ni—Cr—Mo alloying and Nb—V—Ti microalloying component system, has a yield strength of ≥795 MPa, a tensile strength of ≥865 MPa, a −60° C. Charpy V-notch impact energy of ≥140 J, a Z value of ≥35%, and a maximum thickness of 100 mm, and can be used to manufacture racks for offshore platforms.

Dependencies are inferred from the claim text.